Pressure air positioned furnace lighter with automatic pressure air purging



Oct. 26, 1954 L. LEACH 2,692,642

PRESSURE AIR POSITIONED FURNACE LIGHTER WITH AUTOMATIC PRESSURE AIR PURGING Filed Nov. 16, 1950 3 Sheets-Sheet l INVENTOR Z eszer L. 1 each BY 01W ATTORNEY Oct. 26, 1954 1.. L. LEACH 2,692,642

PRESSURE AIR POSITIONED FURNACE LIGHTER WITH AUTOMATIC PRESSURE AIR PURGING 5 Sheets-Sheet 2 Filed Nov. 16, I950 4 i5iiiiiazizs INVENTOR l escer Z. L each BY fLM ATTORNEY Oct. 26, 1954 LEACH 2,692,642

PRESSURE AIR POSITIONED FURNACE LIGHTER WITH AUTOMATIC PRESSURE AIR PURGING Filed Nov. 16, 1950 3 Sheets-Sheet 3 .WQ 3 g R J. JJP A A m AA mm A N ll :I: h E w aw ME 4 WE a w Z ester l. L 9470/: BY WWW ATTORNEY Patented Oct. 26, 1954 PRESSURE AIR POSITIONED FURNACE LIGHTER WITH AUTOMATIC PRES- SURE AIR PURGING Lester L. Leach, Akron,

Babcock & Wilcox Com Ohio, assignor to The pany, New York, N. Y.,

a corporation of New Jersey Application November 16, 1950, Serial No. 195,993

12 Claims.

This invention relates to ignition apparatus and, more particularly, to a retractable furnace lighter embodying novel means for effecting a predetermined operational sequence and automatic purging.

With the increase in the size of furnace, particularly for steam power plants, manual lighting of the furnaces has become hazardou and impractical. This is particularly so in the case of furnaces burning liquid, gaseous or pulverized fuel, and it has been proposed to light or touch off these furnaces by means of remotely controlled mechanical lighters, usually of the type including a liquid fuel atomizing nozzle and associated ignition electrodes.

However, the development of such mechanical lighters and operating mechanism and controls therefor has presented problems due to the necessity of assuring a predetermined procedural sequence in lighting the furnaces. For example, th operating mechanism for such mechanical lighters must be so designed that the lighters are normally withdrawn from the vicinity of the fuel burner to prevent damage to the lighters by the heat of the furnace. The lighter must be fully projected or inserted into the furnace adjacent the main fuel burner when fuel from the latter is to be ignited, or else there is danger of non-functioning of the lighter arrangement due to its not being in close enough relation to the burner. The fuel supply to the lighter should not be initiated until the lighter is in proper posi-- tion, and should be turned off, and the lighter fuel line purged, before the lighter is fully retracted following ignition of the main burner.

To accomplish the desired operational sequence, prior art mechanical atomizing liquid fuel lighters have included cylinder and piston arrangements for advancing and retractin the lighter assemblies. Various means, such as solenoid controlled valves or mechanically interlocked valves, have been used to control the piston operation, admission and cutoff of fuel, and flow of purging fluid, generally air, through the atomizer. The pistons have been operated by high pressure air or by the fuel under pressure, and the purging has been effected prior to the lighter projection or upon retraction.

The lighter of the present invention includes a mechanical atomizer construction reciprocable by an air operated piston. The reciprocating structure has a port so arranged that, in the operative or fully extended position of the lighter, the port comes into operative relation with the fuel supply. During retraction, and before the reciprocating structure is fully retracted, the port comes into operative relation with the pressure air supply for the piston. Thus, the atom izer construction is automatically air purged during its retraction.

More specifically, the fuel pipe and its enclosing l ghter barrel are secured in unitary relation with a piston and extend through the end of a cylinder in the same manner as a piston rod. Surrounding the lighter barrel just beyond the cylinder is an annular fuel chamber embracing the barrel. The inner end of the fuel pipe communicates with a port in the side of the barrel and this port registers with the fuel chamber only when the lighter barrel is fully extended. When the pressure fluid (air) is selectively applied to move the piston toward the retracted position, the port in the side of the barrel moves into the cylinder and the pressure air, which is also acting against the piston, enters the fuel pipe through the port and is discharged through the nozzle to purge residual fuel therefrom.

A pair of ignition electrodes are associated with the atomizer nozzle and one of these electrodes is connected to a source of electric potential through a switch which is operated through a lost motion connection to the lighter barrel only when the barrel has been fully extended.

For an understanding of the invention principles, reference is made to the following description of a typical embodiment thereof as illustrated in the accompanying drawings.

In the drawings:

Fig. l is an elevation view of a lighter embodying the invention as mounted in a furnace end in the extended or operative position;

Fig. 2 is an outer end elevation view of the lighter;

Fig, 3 is an inner end elevation view of the lighter;

Fig. 4 is a composite longitudinal sectional view of the lighter illustrating the fuel admission arrangement of the lighter, with the operating mechanism, to the left of the section line 55 in the advanced position and the elements to the right of section line 5-5 in the retracted position;

Fig. 5 is a view on Fig. 6 is a plan view of shown in Fig. 5; and

Fig. I is a schematic diagram illustrating the controls for the lighter.

Referring more particularly to Figs. 1 through 5 of the drawings, lighter assembly generally indicated at It is shown in operative relation to a. main fuel burner l5 mounted adjacent an aperture l in a wall of a furnace l2.

Main burner i5 is illustrated as a well known pulverized coal burning type including a primary air and coal pip is, and the detailed construction thereof forms no part of the present invention, being familiar to those skilled in the art.

Lighter assembly I is a mechanical liquid fuel atomizer unit, of a well known construction, hav ing a barrel l3 enclosing a fuel pipe or conduit M and extending forwardly. A pair of ignition electrodes l6 and H are arranged in operative association adjacent the fuel atomization tip of pipe I 4. Electrode I is preferably welded or brazed to barrel l3, whereas electrode I! is supported on barrel l3 through an insulator (8.

Both barrel [3 and insulator l8 are mounted through a substantially circular supporting plate 2!, fitting within a tubular guiding casing 22 of the line 5-5 of Fig. 4;

the lighter elements the atomizer unit, and having slots receiving radially projecting elongated guide runners 23 which bear on the inner surface of casing 22.

The outer end of casing 22 is secured to a somewhat larger cylinder housing 24, the juncture therebetween being formed by a frustoconical transition piece 25. A mounting plate 21 embraces and is secured to housing 24. The housing 24 extends through an aperture 28 in wall section of the secondary air chamber surrounding pipe l9. Wall section 25 includes a metallic casing, generally indicated at 3|, sur rounding refractory insulating material 32. The secondary air chamber and the main burner housing l9 are mounted in an aperture 33 in the outer wall 34 of furnace l2. Plate 21 is secured against the outer surface of wall section 25, a suitable gasket 36 being interposed between flange or plate 2'! and the wall section. It will be noted that plate 21 is so disposed on housing 24 that lighter assembly l0 extends in s converging relation to main burner l5 so that the inner ends of assembly l5 and burner l5 are in relatively close relation in the operative or extended position of the lighter.

The barrel l3 extends through casing 22 and housing 2 and its outer end is secured to mechanism for advancing and retracting the barrel and fuel pipe relative to the inner end of casing 22 and the inner end of main burner l5. The electrodes 15 and H are arranged to move as a unit with the lighter barrel, electrode l6 being secured directly to the barrel and electrode i! being supported in insulators l8, 3'! and 38 secured to the lighter barrel.

The operating mechanism, generally indicated at 40, includes a pressure air cylinder 4i having therein a piston 42 provided with rings $3. The inner end of cylinder 4| is fitted in a recess M in a relatively heavy tubular fuel supply and guide member 45, described more fully hereinafter. The inner end of member 45 is bolted to a flange of a supporting bracket including a sleeve 4'! and an inner flange 48 in turn bolted to a collar 49 on the outer end of housing 22.

The inner end of barrel [3 is secured into a 4 latch block 5| secured to the end of a hollow piston rod 52 extending through an axial passage 53 in member 45 and threaded into piston 42. A set screw 54 looks rod 52 to piston 42.

Intermediate the ends of member 45, an annular fuel admission chamber member 55 is mounted in passage 53 and sealingly embraces tubular piston rod 52. Chamber member 55 is an inwardly facing channel in cross section, the base of the channel being formed with ports 55 which register with a circumferential fuel admission passage 5'! formed in the surface of passage 53. Fuel enters passage 51 through a radial fuel port 58 having the end of a fuel supply pipe 58 threaded thereinto. Sealing rings iii are disposed in passage 53 embracing rod 52 and are held in place by a clamping ring 52 threaded into a ring 53 bolted into a recess in the inner end of member 45.

Fuel enters pipe 14 from chamber 55 in the following manner. An elongated plug 55 is threaded into the outer end of hollow rod 52, a nut head 66 being provided for this purpose. Plug 65 has grooves 61 for receiving suitable sealing packing and, in the projected position of barrel IS, the inner end of plug is beyond fuel chamber 55. Rod 52 has a port 68 which, in the fully projected position of barrel l3, registers with fuel chamber 55. Plug 55 has a circumferential groove 59 registering with port 68. Radial passages H connect groove 69 to a central passage 72 which communicates with a threaded opening 13 in the inner end of plug 55. The outer end of fuel pipe 14 is threaded into opening 13 thus communicating with port 68.

Operating air for mechanism 40 is provided, for movement to the lighter retracting position, by means of a pipe 16 threaded into a port in member 45 connected by a passage TI to the interior of cylinder 4!. Air for projecting the lighter assembly is provided by a pipe 78 which communicates with the interior of the cylinder through a cylinder head 19 on the outer end of cylinder M. The outer end of the cylinder is closed by a head 8i clamped against the end of the cylinder by a pressure clamp 82 mounted in a U-shaped bracket 83 pivoted on flange or head '19. It should be noted that fuel pipe l4 flts through barrel l3 and is of less diameter than piston rod 52. Hence, by releasing clamp $32, swinging bracket 83 to one side, and turning the head 56 to unscrew plug 65 from rod 52, the assembly of plug 65 and fuel pipe 14 may be withdrawn through the outer end of lighter assembly ill for inspection, repair, cleaning, or replacement of the components.

Latch block 5! has a notch 85 cooperable with a keeper 8'! mounted in a tube 88 secured to sleeve 4?. The keeper has a guide stem 89 extending d wnwardly through a plug Si in bracket 88, and is biased to the locking position by a spring 98. A pin 92 engaging a longitudinal groove 93 in the side of keeper 8'! maintains the latter properly aligned with notch 85. When retracted, the assembly is automatically latched by keeper 8'! engaging in notch 86 of block 5|.

Application of electric potential to electrode H is accomplished in the following manner, referring more particularly to Figs. 5 and 6. A source of potential is connected to one terminal of a normally closed switch 95 mounted on a bracket 93 secured to flange 66. This bracket serves as a pivot support for a channel shaped operator 91 engaging the stem 98 of switch 95. Operator 9? has pins 99 fitted in an outwardly channeled ring I III secured to the end of a rod I02. A spring I03 surrounds rod I02 and is disposed between ring I! and flange 48 to bias rod I02 outwardly. The rod I02 extends inwardly through flange 48 and through a plate I04 secured to barrel I3, nuts I06 being secured to the rod inwardly of plate I04. The nuts I06 are so adjusted on rod I02 as to be engaged by plate I 04 just before the assembly reaches its fully extended, or operative, position. Thereby, switch 95 is closed only when the lighter assembly is fully extended.

The other terminal of switch 95 is connected to the end of a conductor I01 mounted through an insulator I 08 secured in flange 48. Conductor I01 is bent laterally and then parallel with electrode I1. The end of this electrode beyond insulator 3B is electrically connected to a spring brush III] bearing against conductor I01. Thus, as the electrode assembly is advanced and retracted, the sliding contact IIO maintains connection between conductor I08 and electrode I1.

The operation of the elements so far described is as follows: With the assembly in the retracted position. air is admitted to cylinder 4| through pipe 18. This moves piston 42 to the right, or inwardly. As the piston reaches its limit of movement, port 68 in rod 52 registers with fuel admission chamber 55 and fuel is thereby admitted to pipe I4, being sprayed from the atomizing tip of the fuel pipe. At the same time, plate I 54 will have engaged nuts I05 to pull rod I02, compressing spring I03 and swinging operator 91 to close switch 95. This applies a high potential between electrodes I6 and I1 to provide the ignition spark.

In retracting the assembly, the fuel supply is interrupted and air is supplied to pipe 16. As piston 42 moves outwardly, I04 disengages nuts I05 allowing switch 95 to open. At the same time, port 58 is moved out of registry with fuel chamber 55. At a point intermediate the extended and retracted positions of the assembly, port 58 passes beyond the outermost sealing rings GI and is in communication with the inner end of cylinder 4i. Some of the pressure air being supplied to this end of the cylinder enters through port 68 into pipe I4 and is discharged outwardly through the atomizing tip. This pressure air purges the fuel pipe and its tip of any residual fuel or foreign matter. Furthermore, such purging takes place automatically during each retraction of the assembly without use of any mechanical or electro-mechanical air valves being needed. Thereby, defective operation due to failure of control valves under conditions of high temperature is completely avoided, thus increasing the reliability of the lighter assembly.

The control arrangements for the lighter are illustrated in the schematic diagram of Fig. 7. Referring to this figure, control is effected through the medium of a start contactor I and a stop contactor I30. Power is supplied from a supply line iZI having in one leg a switch I22 which is interlocked with the draft fan control of the furnace in such manner that transformer I25 will be energized only when the draft fan controls are started.

Secondary winding I25 supplies power to conductors I21, I28 for one group of lighter assemblies Iii. Leads I31 may be provided for the energization of additional lighter assemblies. The start contactor I20 is operated by means of push button I35. One terminal of push button I35 is connected to conductor I21 through conductor I32, normally closed contact 9 of the stop contactor I30, conductor I34, a pressure operated switch I36 and conductor I31. Switch I36 is operated by the pressure of the fuel oil supply eiTective in branch line I38, and is so set that the switch will be closed only when the fuel oil pressure is at a predetermined value, such as 100 p. s. i. The other terminal of switch I35 is connected by a conductor I30 to one terminal of the contactor operating coil I40 whose other terminal is connected to line. I28. When button I35 is depressed, contactor I20 is operated closing its several normally open contacts.

Closure of contact a keeps a holding circuit around push button I35 so that the latter may be released. Contacts b and 0 connect the secondary potential to conductors I4I across which are connected the operating coil I'42 of a solenoid operated oil valve I43 and the operating coil I44 of an air selector I45. When valve I43 is open, oil under pressure is supplied from inlet line I46 to main I41 and pipe 60 connected to member 45 and in communication with fuel chamber 55. Energization of coil I44 rotates valve I45 counterclockwise from the illustrated position to connect air pipe 18 to air line I 48 and connect air pipe 15 to exhaust. Closure of contacts 41 and e connects the secondary line potential to conductors I5I. Connected across these conductors is the operating coil I52 of an air valve I53 disposed between air line I48 and air supply pipe I54, a filter I55 being provided in advance of valve I53. The ignition transformers I56 are also connected to lines I5I through the medium of safety switches I51. Switches I51 provide for disconnection of the lighter assemblies from the electric potential source so that the assemblies may be inspected, cleaned, or repaired without risk of electric shock to the maintainer. However, potential is not applied to the electrodes until such time as switch has been closed by inward movement of the lighter assembly to connect conductor I01 to its ignition transformer. Contacts f are included in an interlock arrangement with the push button control for the energizing circuit of the pulverizer supplying fuel to the main burner I5, the arrangement being such that, when the pulverizer has been started by contacts 1, the circuit will remain closed even though contacts f are reopened.

Retraction of the lighter assembly is effected by depressing push button I50 to energize stop contactor I30. Push button I00 has one terminal connected to line I21 through conductor I32. A conductor I5I connects the other push button terminal to the operating coil I02 of the stop contactor, the other terminal of the energizing coil being connected to line I20 through a conductor I63. When coil IE2 is energized, it opens normally closed contacts g and closes contacts h, 7', k and Z. Opening of contact g breaks the holding circuit of the start contactor. Contacts h and k, which are connected to the secondary transformer circuits I32 and I53, energize the air valve coil I52 through conductors I54. Air valve I45, when the start contactor is deenergized, will have returned to the position illustrated in Fig. 7 in which pipe 15 is connected to the pressure air and pipe 18 is vented. Thus, the mechanism 40 will retract the lighter assembly, with the pressure air discharging through fuel pipe I4 after the assembly reaches a position intermediate its operative and inoperative positions. Such retraction will also open the switch 95 to disconnect the energizing potential from electrode IT. The normally closed contact m is a slow release contact controlled by a coil I55. This coil is energized when contacts 9' and n are closed, contact I in series with contact m completing a holding circuit for stop contactor around the push button I60. After a preset interval, which is determined in accordance with the desired length of air purge time, contact m opens breaking the holding circuit for the stop contactor and restoring all of the elements to the position shown in Fig. '7.

While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the invention principles, it will be understood that the invention may be otherwise embodied without departing from such principles.

I claim:

1. A fuel lighter comprising, in combination, a fuel pipe; pressure fluid operating means operable to advance and retract said fuel pipe between a retracted inoperative position and an extended operative position; a source of pressure fluid in selective communication with said operating means; a source of fuel; means operable only in the operative position -of said fuel pipe to establish a connection between said source of fuel and said fuel pipe; and means perable, when said pressure fluid is acting on said operating means to retract said fuel pipe toward said retracted position and said fuel pipe is in a position intermediate said retracted and extended positions, to establish communication between said source of pressure fluid and said fuel pipe to purge the latter of residual fuel.

2. A fuel lighter comprising, in combination, a fuel pipe; pressure fluid operating means operable to advance and retract said fuel pipe between a retracted inoperative position and an extended operative position; a source of pressure fluid in selective communication with said operating means; a source of fuel; means operable only in the operative position of said fuel pipe to establish a connection between said source of fuel and said fuel pipe; and means, including said operating means operable, when said pressure fluid is acting on said operating means to retract said fuel pipe toward said retracted position and said fuel pipe is in a position intermediate said retracted and extended positions, to establish communication between said source of pressure fluid and said fuel pipe to purge the latter of residual fuel.

3. A fuel lighter comprising, in combination, a fuel pipe; a pressure fluid operated cylinder and piston arrangement operable to advance and retract said fuel pipe between a retracted inoperative position and an extended operative position; a source of pressure fluid in selective communication with said cylinder on either side of said piston; a source of fuel; means operable only in the operative position of said fuel pipe to establish a connection between said source of fuel and said fuel pipe; and means operable, when said pressure fluid is acting on said piston to retract said fuel pipe toward said retracted position and said fuel pipe is in a position intermediate said retracted and extended positions, to establish communication between said cylinder on the pressure side of said piston and said fuel pipe to purge the latter of residual fuel.

4. A fuel lighter comprising, in combination, a fuel pipe having port means therein; a cylinder; a piston in said cylinder connected to said fuel pipe and operable to advance and retract said fuel pipe between a retracted inoperative position and an extended operative position; a source of pressure fluid in selective communica tion with said cylinder on either side of said piston; a source of fuel; and means operable only in the operative position of said fuel pipe to establish a connection between said source of fuel and the port means in said fuel pipe; the fuel pipe port means communicating with the interior of said cylinder when said fuel pipe is between said retracted position and a position intermediate said retracted and extended positions whereby, when the pressure fluid is acting on said piston during the latter portion of the retraction stroke of said piston, pressure fluid will enter said fuel pipe to purge the latter of residual fuel.

5. A fuel lighter comprising, in combination, a fuel pipe having port means therein; a cylinder; a piston in said cylinder connected to said fuel pipe and operable to advance and retract said fuel pipe between a retracted inoperative position and an extended operative position; a source of pressure fluid in selective communication with said cylinder on either side of said piston; a source of fuel; and a fuel chamber embracing said pipe beyond said cylinder and connected to said source of fuel, said chamber being so located as to register with said port means only in the extended position of said fuel pipe; the fuel pipe port means communicating with the interior of said cylinder when said fuel pipe is between said retracted position and a position intermediate said retracted and extended positions whereby, when the pressure fluid is acting on said piston during the latter portion of the retraction stroke of said piston, pressure fluid will enter said fuel pipe to purge the latter of residual fuel.

6. A fuel lighter comprising, in combination, a fuel pipe having port means therein intermediate its ends and a fuel passage extending from the port means to the outer end of the fuel pipe; a cylinder; a piston in said cylinder connected to said fuel pipe and operable to advance and retract said fuel pipe between a retracted inoperative position and an extended operative position; a source of pressure fluid in selective communication with said cylinder on either side of said piston; a source of fuel; and a fuel chamber embracing said pipe beyond said cylinder and connected to said source of fuel; said port means being so located relative to said cylinder and fuel chamber as to register with said chamber only in the extended position of the fuel pipe and to communicate with the cylinder interior when the fuel pipe is between its retracted position and a position intermediate its retracted and extended positions; whereby fuel will enter said pipe only in the extended position of the latter and, when the pressure fluid is acting on said piston during the latter portion of the retraction stroke of said piston, pressure fluid will enter said fuel pipe to purge the latter of residual fuel.

7. A fuel lighter comprising, in combination, a fuel pipe having port means therein intermediate its ends and a fuel passage extending from the port means to the outer end of the fuel pipe; a cylinder; a piston in said cylinder connected to said fuel pipe and operable to advance and retract said fuel pipe between a retracted inoperative position and an extended operative position; a source of pressure fluid in selective communication with said cylinder on either side of said piston; a source of fuel; a fuel chamber embracing said pipe beyond said cylinder and connected to said source of fuel; said port means being so located relative to said cylinder and fuel chamber as to register with said chamber only in the extended position of the fuel pipe and to communicate with the cylinder interior when the fuel pipe is between its retracted position and a position intermediate its retracted and extended positions; whereby fuel will enter said pipe only in the extended position of the latter and, whenthe pressure fluid is acting on said piston during the latter portion of the retraction stroke of said piston, pressure fluid will enter said fuel pipe to purge the latter of residual fuel; fuel ignition means in operative relation with the outer end of said fuel pipe; a source of electric potential; a normally open switch connected between said potential source and said ignition means; and a switch operator controlled by said fuel pipe and operable to close said switch only when said fuel pipe is fully extended.

8. A fuel lighter comprising, in combination,

a fuel pipe; pressure fluid operating means operable to advance and retract said fuel pipe between a retracted inoperative position and an extended operative position; a source of pres sure fluid in selective communication with said operating means; a source of fuel; means operable only in the operative position of said fuel pipe, to establish a connection between said source of fuel and said fuel pipe; means operable, when said pressure fluid is acting on said operating means to retract said fuel pipe toward said retracted position, to establish communication between said source of pressure fluid and said fuel pipe to purge the latter of residual fuel; fuel ignition means in operative relation with the outer end of said fuel pipe; a source of electric potential; a normally open switch connected between said potential source and said ignition means; and a switch operator controlled by said fuel pipe and operable to close said switch only when said fuel pipe is fully extended.

9. A fuel lighter comprising, in combination, a fuel pipe; pressure fluid operating means operable to advance and retract said fuel pipe between a retracted inoperative position and an extended operative position; a source of pressure fluid in selective communication with said operating means; a source of fuel; means operable only in the operative position of said fuel pipe, to establish a connection between said source of fuel and said fuel pipe; means operable, when 4 said pressure fluid is acting on said operating means to retract said fuel pipe toward said retracted position and said fuel pipe is in a position intermediate said retracted and extended positions, to establish communication between said source of pressure fluid and said fuel pipe to purge the latter of residual fuel; releasable latch means associated with said pipe and operable to releasably latch the pipe in its retracted position; fuel ignition means in operative relation with the outer end of said fuel pipe; a source of electric potential; a normally open switch connected between said potential source and said ignition means; and a switch operator controlled by said fuel pipe and operable to close said switch only when said fuel pipe is fully extended.

10. A fuel lighter comprising, in combination, a fuel pipe having port means therein intermediate its ends and a fuel passage extending from the port means to the outer end of the fuel pipe; a cylinder; a piston in said cylinder connected to said fuel pipe and operable to advance and retract said fuel pipe between a retracted inoperative position and an extended operative position; a source of pressure fluid in selective communication with said cylinder on either side of said piston; a source of fuel; a fuel chamber embracing said pipe beyond said cylinder and connected to said source of fuel; said port means being so located relative to said cylinder and fuel chamber as to register with said chamber only in the extended position of the fuel pipe and to communicate with the cylinder interior when the fuel pipe is between its retracted position and a position intermediate its retracted and extended positions; whereby fuel will enter said pipe only in the extended position of the latter and, when the pressure fluid is acting on said piston during the latter portion of the retraction stroke of said piston, pressure fluid will enter said fuel pipe to purge the latter of residual fuel; releasable latch means associated with said pipe and operable to releasably latch the pipe in its retracted position; fuel ignition means in operative relation with the outer end of said fuel pipe; a source of electric potential; a normally open switch connected between said potential source and said ignition means; and a switch operator controlled by said fuel pipe and operable to close said switch only when said fuel pipe is fully extended.

11. A fuel lighter comprising, in combination, a fuel pipe having port means therein intermediate its ends and a fuel passage extending from the port means to the outer end of the fuel pipe; a cylinder; a piston in said cylinder connected to said fuel pipe and operable to advance and retract said fuel pipe between a retracted inoperative position and an extended operative position; a source of pressure fluid in selective communication with said cylinder on either side of said piston; a source of fuel; a housing secured to the outer end of said cylinder and having an axial passage receiving said fuel pipe; a fuel chamber within the housing passage and embracing the fuel pipe; means connecting said chamber to said source of fuel; a fuel chamber embracing said pipe beyond said cylinder and connected to said source of fuel; said port means being so located relative to said cylinder and fuel chamber as to register with said chamber only in the extended position of the fuel pipe and to communicate with the cylinder interior when the fuel pipe is between its retracted position and a position intermediate its retracted and extended positions; whereby fuel will enter said pipe only in the ex" tended position of the latter and, when the pressure fluid is acting on said piston during the latter portion of the retraction stroke of the piston, pressure fluid will enter the fuel pipe to purge the latter of residual fuel.

12. A fuel lighter comprising, in combination, a fuel pipe having port means therein intermediate its ends and a fuel passage extending from the port means to the outer end of the fuel pipe; a cylinder; a piston in said cylinder connected to said fuel pipe and operable to advance and retract said fuel pipe between a retracted inoperative position and an extended operative position; a source of pressure fluid in selective communication with said cylinder on either side of said piston; a source of fuel; a housing secured to the outer end of said cylinder and having an axial passage receiving said fuel pipe; a fuel chamber within the housing passage and embracing the fuel pipe; means connecting said chamber to said source of fuel; and sealing means in said passage engaging the surface of said fuel pipe; a fuel chamber embracing said pipe'beyond said cylinder and connected to said source of fuel; said port means being so located relative to said cylinder and fuel chamber as to register with said chamher only in the extended position of the fuel pipe and to communicate with the cylinder interior when the fuel pipe is between its retracted position and a position intermediate its retracted and extended positions; whereby fuel will enter said pipe only in the extended position of the latter and, when the pressure fluid is acting on said pis ton during the latter portion of the retraction stroke of the piston, pressure fluid will enter the fuel pipe to purge the latter of residual fuel.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 10 2,047,523 Scranton et a1 July 14, 1936 2,382,483 Holden Aug. 14, 1945 2,596,944 Shellenberger et a1. May 13, 1952 

